Pinto says pursuit operations are continuing but there has been no encounter so far with the gunmen.

A 3-year-old boy and his father died from wounds suffered in a brazen attack by Abu Sayyaf extremists on Filipinos celebrating the end of Ramadan, raising the toll Tuesday to 23 dead, officials said.

About 40 to 50 Abu Sayyaf militants armed with assault rifles opened fire Monday on some 50 villagers as they traveled on a southern road to visit relatives during the holiday ending the Muslim holy month.

Marine Brig. Gen. Martin Pinto said six villagers who were wounded remained in the hospital Tuesday following the militants’ bloodiest attack in recent years. Three other slightly wounded villagers have gone home after treatment. The attack occurred in a coastal village in Talipao town in predominantly Muslim Sulu province, where the extremists have survived in jungle camps despite years of U.S.-backed Philippine military offensives.

Pinto says pursuit operations are continuing but there has been no encounter so far with the gunmen. “It’s not that easy, this is a vast area,” he said in a telephone interview. But he said government troops are moving and “we will bring them to justice.” Initial military reports said 10 civilian security force personnel were with the villagers, but Pinto said Tuesday the information was being verified, including if six men among the dead were members of the Barangay Peacekeeping Action Team.

The motive for the attack was unclear. Officials say it could be part of a violent clan war or retaliation by the extremists against the civilian security team, which has backed the military in previous clashes where Abu Sayyaf members were killed. Sulu Vice Governor Abdusakur Tan condemned the attack and alleged that supporters of a village official he did not name, in cooperation with the Abu Sayyaf, may be behind the “barbaric act.”

“This is un-Islamic and very satanic,” Tan said. “After going through the holy month of Ramadan, even animals could hardly inflict damage of such magnitude.” The Abu Sayyaf, which has about 300 armed fighters split into several factions, was organized in the early 1990s, but has been crippled by government operations and endures largely by conducting ransom kidnappings. It now holds about 10 hostages, including two German tourists seized in April and two birdwatchers, one Dutch and the other Swiss, who were kidnapped two years ago.

The Abu Sayyaf is one of about four smaller Muslim insurgent groups outside of a peace deal signed by the Philippine government in March with the main rebel group, the 11,000-strong Moro Islamic Liberation Front that calls for the creation of a more powerful and potentially larger autonomous region for minority Muslims in the south of the largely Roman Catholic country.